So I went to Lowes today to look at dehumidifies, and I see they now classify them by "pints per/day" of water removed from the air. I have always been used to seeing them list a volume or sq ft for the size of the room you are putting it in. I asked the Lowes guy and he said a standard full size basement you would need to pull 50-70 pints per day (which is the biggest model they had). The units they sold were listed at 30ppd, 45ppd and 70 ppd and that was at the highest setting. The other catch here is at those rates you would have to empty the catch bin multiple times and day to get those ppd rates, or attach a hose to dump into your sump crock.

So my question is how do I convert Pints/day to the approx sqft of my basement and buy the correct sized unit I need??

You can not base ppd on sq ft. To determine the ppd you need to know many factors such as air temp and humidity to determine the grains per inch in the air. the dehumidifier will not pull 70 pints by itself. you would also need lots of air movement to get that moisture to the machine. Also that much moisture is definitely unhealthy and damaging. 70 pints is getting into the categories we pull with our very expensive commercial units plus 10 air movers used for disaster restoration .

But yes get the big one. i would recommend not buying from lowes and check some forums and buy direct over big box. you will get a much better unit.

What Silver Bullet said. Get the biggest you can afford/fit where you want it. Something is better than nothing.
Who does Silver Bullet work for. I just left the restoration industry after 12 years due to lack of work around here, wondering how others are doing.